Desloratadine

Identification

Name

Desloratadine

Accession Number

DB00967 (APRD00324)

Type

Small Molecule

Groups

Approved, Investigational

Description

Desloratadine is a second generation, tricyclic antihistamine that which has a selective and peripheral H1-antagonist action. It is the active descarboethoxy metabolite of loratidine (a second generation histamine). Desloratidine has a long-lasting effect and does not cause drowsiness because it does not readily enter the central nervous system.

Pharmacology

Indication

For the relief of symptoms of seasonal allergic rhinitis, perennial (non-seasonal) allergic rhinitis. Desloratidine is also used for the sympomatic treatment of pruritus and urticaria (hives) associated with chronic idiopathic urticaria.

Desloratadine is a long-acting second-generation H1-receptor antagonist which has a selective and peripheral H1-antagonist action. Histamine is a chemical that causes many of the signs that are part of allergic reactions, such as the swelling of tissues. Histamine is released from histamine-storing cells (mast cells) and attaches to other cells that have receptors for histamine. The attachment of the histamine to the receptors causes the cell to be "activated," releasing other chemicals which produce the effects that we associate with allergies. Desloratadine blocks one type of receptor for histamine (the H1 receptor) and thus prevents activation of cells by histamine. Unlike most other antihistamines, Desloratadine does not enter the brain from the blood and, therefore, does not cause drowsiness.

Mechanism of action

Like other H1-blockers, Desloratadine competes with free histamine for binding at H1-receptors in the GI tract, uterus, large blood vessels, and bronchial smooth muscle. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms (eg. nasal congestion, watery eyes) brought on by histamine.

Desloratadine (a major metabolite of loratadine) is extensively metabolized to 3-hydroxydesloratadine, an active metabolite, which is subsequently glucuronidated. Approximately 87% of a 14C-desloratadine dose was equally recovered in urine and feces.

Bachert C: A review of the efficacy of desloratadine, fexofenadine, and levocetirizine in the treatment of nasal congestion in patients with allergic rhinitis. Clin Ther. 2009 May;31(5):921-44. doi: 10.1016/j.clinthera.2009.05.017. [PubMed:19539095]

Taxonomy

Description

This compound belongs to the class of organic compounds known as benzocycloheptapyridines. These are aromatic compounds containing a benzene ring and a pyridine ring fused to a seven membered carbocycle.